WO2014179677A1 - Extended lifetime ion source - Google Patents
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- WO2014179677A1 WO2014179677A1 PCT/US2014/036558 US2014036558W WO2014179677A1 WO 2014179677 A1 WO2014179677 A1 WO 2014179677A1 US 2014036558 W US2014036558 W US 2014036558W WO 2014179677 A1 WO2014179677 A1 WO 2014179677A1
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- WIPO (PCT)
- Prior art keywords
- ion source
- source chamber
- insert
- reactive
- cathode
- Prior art date
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- 229910052736 halogen Inorganic materials 0.000 claims abstract description 40
- 150000002367 halogens Chemical class 0.000 claims abstract description 40
- 239000003870 refractory metal Substances 0.000 claims abstract description 34
- 239000000463 material Substances 0.000 claims abstract description 15
- 150000002500 ions Chemical class 0.000 claims description 187
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 claims description 30
- 229910052721 tungsten Inorganic materials 0.000 claims description 29
- 239000010937 tungsten Substances 0.000 claims description 29
- 229910052710 silicon Inorganic materials 0.000 claims description 27
- 239000010703 silicon Substances 0.000 claims description 26
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 25
- 238000000034 method Methods 0.000 claims description 9
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 claims description 4
- 229910052750 molybdenum Inorganic materials 0.000 claims description 4
- 239000011733 molybdenum Substances 0.000 claims description 4
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 claims description 4
- 210000002381 plasma Anatomy 0.000 description 64
- 229910015900 BF3 Inorganic materials 0.000 description 25
- WTEOIRVLGSZEPR-UHFFFAOYSA-N boron trifluoride Chemical compound FB(F)F WTEOIRVLGSZEPR-UHFFFAOYSA-N 0.000 description 24
- 239000007789 gas Substances 0.000 description 23
- 238000001819 mass spectrum Methods 0.000 description 23
- 238000005530 etching Methods 0.000 description 11
- 229910052731 fluorine Inorganic materials 0.000 description 11
- 239000011737 fluorine Substances 0.000 description 11
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 description 10
- 239000000047 product Substances 0.000 description 10
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 8
- 229910052782 aluminium Inorganic materials 0.000 description 7
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 7
- ABTOQLMXBSRXSM-UHFFFAOYSA-N silicon tetrafluoride Chemical compound F[Si](F)(F)F ABTOQLMXBSRXSM-UHFFFAOYSA-N 0.000 description 6
- 239000002243 precursor Substances 0.000 description 5
- -1 BF3 ions Chemical class 0.000 description 4
- 229910004014 SiF4 Inorganic materials 0.000 description 4
- 229910052796 boron Inorganic materials 0.000 description 4
- 230000008859 change Effects 0.000 description 4
- 238000010494 dissociation reaction Methods 0.000 description 4
- 230000005593 dissociations Effects 0.000 description 4
- 230000003628 erosive effect Effects 0.000 description 4
- 238000002474 experimental method Methods 0.000 description 4
- 230000007935 neutral effect Effects 0.000 description 4
- 239000007787 solid Substances 0.000 description 4
- 238000004544 sputter deposition Methods 0.000 description 4
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 3
- 238000000605 extraction Methods 0.000 description 3
- XRXPBLNWIMLYNO-UHFFFAOYSA-J tetrafluorotungsten Chemical class F[W](F)(F)F XRXPBLNWIMLYNO-UHFFFAOYSA-J 0.000 description 3
- 229910006160 GeF4 Inorganic materials 0.000 description 2
- 229910021180 PF3 Inorganic materials 0.000 description 2
- 229910004016 SiF2 Inorganic materials 0.000 description 2
- 229910052785 arsenic Inorganic materials 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- WUWOPJNIAKTBSJ-UHFFFAOYSA-N diboron tetrafluoride Chemical compound FB(F)B(F)F WUWOPJNIAKTBSJ-UHFFFAOYSA-N 0.000 description 2
- MGNHOGAVECORPT-UHFFFAOYSA-N difluorosilicon Chemical compound F[Si]F MGNHOGAVECORPT-UHFFFAOYSA-N 0.000 description 2
- 239000002019 doping agent Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000010891 electric arc Methods 0.000 description 2
- 238000010849 ion bombardment Methods 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- WKFBZNUBXWCCHG-UHFFFAOYSA-N phosphorus trifluoride Chemical compound FP(F)F WKFBZNUBXWCCHG-UHFFFAOYSA-N 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 230000003595 spectral effect Effects 0.000 description 2
- PPMWWXLUCOODDK-UHFFFAOYSA-N tetrafluorogermane Chemical compound F[Ge](F)(F)F PPMWWXLUCOODDK-UHFFFAOYSA-N 0.000 description 2
- IRPGOXJVTQTAAN-UHFFFAOYSA-N 2,2,3,3,3-pentafluoropropanal Chemical compound FC(F)(F)C(F)(F)C=O IRPGOXJVTQTAAN-UHFFFAOYSA-N 0.000 description 1
- KLZUFWVZNOTSEM-UHFFFAOYSA-K Aluminum fluoride Inorganic materials F[Al](F)F KLZUFWVZNOTSEM-UHFFFAOYSA-K 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- RQNWIZPPADIBDY-UHFFFAOYSA-N arsenic atom Chemical compound [As] RQNWIZPPADIBDY-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 239000007795 chemical reaction product Substances 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000000151 deposition Methods 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 230000005684 electric field Effects 0.000 description 1
- BHEPBYXIRTUNPN-UHFFFAOYSA-N hydridophosphorus(.) (triplet) Chemical compound [PH] BHEPBYXIRTUNPN-UHFFFAOYSA-N 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 230000003116 impacting effect Effects 0.000 description 1
- 239000007943 implant Substances 0.000 description 1
- 238000002513 implantation Methods 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- 238000005468 ion implantation Methods 0.000 description 1
- 238000010884 ion-beam technique Methods 0.000 description 1
- 230000001788 irregular Effects 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 239000002210 silicon-based material Substances 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
- C23F4/00—Processes for removing metallic material from surfaces, not provided for in group C23F1/00 or C23F3/00
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
- H01J37/30—Electron-beam or ion-beam tubes for localised treatment of objects
- H01J37/305—Electron-beam or ion-beam tubes for localised treatment of objects for casting, melting, evaporating, or etching
- H01J37/3053—Electron-beam or ion-beam tubes for localised treatment of objects for casting, melting, evaporating, or etching for evaporating or etching
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J27/00—Ion beam tubes
- H01J27/02—Ion sources; Ion guns
- H01J27/08—Ion sources; Ion guns using arc discharge
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
- H01J37/02—Details
- H01J37/04—Arrangements of electrodes and associated parts for generating or controlling the discharge, e.g. electron-optical arrangement or ion-optical arrangement
- H01J37/08—Ion sources; Ion guns
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J2237/00—Discharge tubes exposing object to beam, e.g. for analysis treatment, etching, imaging
- H01J2237/02—Details
- H01J2237/022—Avoiding or removing foreign or contaminating particles, debris or deposits on sample or tube
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J2237/00—Discharge tubes exposing object to beam, e.g. for analysis treatment, etching, imaging
- H01J2237/32—Processing objects by plasma generation
- H01J2237/33—Processing objects by plasma generation characterised by the type of processing
- H01J2237/334—Etching
- H01J2237/3341—Reactive etching
Definitions
- Embodiments relate to the field of ion sources. More particularly, the present embodiments relate to an improved lifetime ion source for use with halogen species.
- Ion sources such as indirectly heated cathode (IHC) ion sources are used to generate a variety of ion species including dopant ions that are used for implantation into semiconductor substrates to control their electronic properties.
- Many precursors for dopant ions contain halogen species such as fluorine (BF 3 , B 2 F 4 , GeF 4 , PF 3 , SiF 4 etc), which can create a corrosive environment within an ion source.
- fluorine BF 3 , B 2 F 4 , GeF 4 , PF 3 , SiF 4 etc
- the lifetime of an IHC ion source is typically limited by the lifetime of the cathode and repeller components of the ion source.
- portions of the ion source that are exposed to halogens such as fluorine-containing species may be subject to corrosion.
- ion source components may be constructed at least partially from tungsten that is exposed to fluorine species during operation.
- a halogen cycle may be established that removes tungsten from relatively colder surfaces within the ion source and redeposits the tungsten on relatively hotter surfaces, such as hot electrode surfaces or chamber walls.
- relatively hotter surfaces such as hot electrode surfaces or chamber walls.
- an uncontrollable growth of tungsten may occur on some electrode surfaces, which can result in glitching during operation of the ion source.
- Glitching is a phenomenon in which smooth operation of an ion source is disrupted by arcing that occurs either inside the ion source or in the ion extraction system. Glitching is exacerbated, for example, when sharp tungsten protuberances are grown on electrodes surface.
- an ion source includes an ion source chamber, a cathode disposed within the ion source chamber and configured to emit electrons to generate an arc plasma, and a repeller configured to repel electrons back into the arc plasma.
- the ion source chamber and cathode may comprise a refractory metal.
- the ion source chamber further includes a gas source configured to provide a halogen species to the ion source chamber, and a reactive insert disposed within the ion source chamber.
- the reactive insert is interoperative with the halogen species to yield a first etch rate of the refractory metal material within the ion source chamber under a first set of operating conditions that is less than a second etch rate of the refractory metal material within the ion source chamber under the first set of operating conditions when the reactive insert is not disposed within the ion source chamber.
- a method to operate an ion source comprises providing a halogen species to an ion source chamber of the ion source, where the ion source chamber comprises a refractory metal.
- the method also includes providing a reactive insert within the ion source chamber, the reactive insert configured to react with the halogen species to produce one or more product species, and generating an arc plasma including the reactive species in the ion source chamber, wherein the halogen gas and reactive insert are interoperative to yield a first etch rate of the refractory metal within the ion source chamber under a first set of operating conditions that is less than a second etch rate of the refractory metal within the ion source chamber under the first set of operating conditions when the reactive insert is not disposed within the ion source chamber.
- FIG. 1 A depicts a side view of an exemplary ion source
- FIG. IB depicts a top view of the ion source of FIG. 1A;
- FIG. 2A depicts a mass spectrum of species produced during operation of an exemplary ion source under one set of conditions
- FIG. 2B depicts another mass spectrum of species produced during operation of the exemplary ion source of FIG. 2A under another set of conditions
- FIG. 2C depicts another mass spectrum of species produced during operation of the exemplary ion source of FIG. 2A under the set of conditions of FIG. 2B;
- FIG. 3 depicts another mass spectrum of species produced during operation of the exemplary ion source of an exemplary ion source under an additional set of conditions.
- ion sources are configured to improve performance and/or extend operating life of an ion source.
- Ion sources arranged according to the present embodiments include those ion sources that are constructed from refractory metal materials and designed to operate at elevated temperatures. Included among such ion sources are indirectly heated cathode (IHC) ion sources in which a cathode may operate at temperatures in excess of 2000°C, such as about 2200°C.
- IHC indirectly heated cathode
- the ion sources may be constructed, at least in part, from tungsten, molybdenum, or other refractory metal.
- an ion source constructed from refractory metal is provided with a reactive insert placed within the ion source chamber that is exposed to etching species generated when an arc discharge (arc plasma) is ignited within the ion source chamber.
- a halogen species such as the halogen gas or a product of the halogen gas
- the reactive insert is interoperative in conjunction with the halogen species to reduce etching of refractory metal from within the ion source chamber.
- halogen species refers to any halogen-containing gaseous compound and the derivative of it that might be created in the plasma. This has the beneficial effect of reducing erosion of ion source components, as well as preventing refractory metal regrowth on hot surfaces of the ion source caused by redeposition of etched refractory metal. The reduction of the refractory metal regrowth, in turn, reduces or prevents instability and/or shorting that may be otherwise generated by the regrown refractory metal deposits. As detailed below, the halogen species and/or reactive insert may be operative to generate low ionization potential gas species, where the ionization potential is below about 11 eV.
- the reactive insert may also act as a sacrificial material to generate reaction products with the halogen species and thereby reduce reaction of the halogen species with the refractory metal surfaces, so that during ion source operation etch rate of such surfaces is reduced in comparison to etch rate when the reactive insert is absent.
- FIG. 1A depicts general features of an ion source 100 consistent with the present embodiments.
- the ion source 100 is an indirectly heated cathode (IHC) ion source that includes an ion source chamber 102, which houses a cathode 104, repeller 108, and extraction plate 112 that has an extraction slit 113.
- the ion source 100 also includes a filament 106 to heat the cathode 104.
- species such as gaseous species are provided by gas manifold 110 to the interior 114 of ion source chamber 102 through a gas inlet 111.
- the gas manifold 1 10 may provide feed material in the form of gaseous species or vapor, which is ionizable in the ion source chamber 102.
- suitable feed material includes one or more gaseous compounds of boron (B), carbon (C), phosphorous (P), arsenic (As), silicon (Si), hydrogen (H), and fluorine (F).
- B boron
- C carbon
- P phosphorous
- As arsenic
- Si silicon
- H hydrogen
- fluorine fluorine
- An arc plasma 116 may be generated when the cathode 104 is heated and a potential difference (voltage) applied between ion source chamber 102 and cathode 104 and repeller 108, where the cathode and repeller are held at the same potential.
- the ion source 100 is coupled to various conventional components that are not depicted for clarity, including power supplies for the cathode 104 and filament 106.
- the ion source chamber and components therein including the cathode 104 and repeller 108 are constructed from tungsten, molybdenum, or other refractory metal.
- feed material may be supplied in the form of halogen species.
- the ion source 100 may be employed in a conventional beamline apparatus for ion implantation of B, P, As, Si, or other species, each of which may be derived from a halogen-containing precursor species.
- halogen species that may be used as precursors for ions generated by the ion source 100 include BF 3 , PF 3 , SiF 4 , B 2 F 4 , GeF 4 among other species.
- halogen species include products of another halogen species.
- BF3 gas may be provided to the ion source and BF 3 ions, BF 2 neutrals, BF 2 ions, BF neutrals, BF ions, and F neutrals, F positive and negative ions and other heavy neutral radicals or ions B x F y among others may all be produced through one or more processes from the parent BF 3 gas and are all deemed to be halogen species.
- the embodiments are not limited in this context.
- the ion source 100 includes a pair of reactive inserts 118.
- a first reactive insert 118 is disposed in a first region (upper part) of the ion source chamber 102 while a second reactive insert is disposed in a second region (lower part) of the ion source chamber.
- a single reactive insert or three or more reactive inserts may be included in an ion source.
- a pair of reactive inserts may be located in a respective left region and right region of the ion source chamber 102 as viewed from the perspective of FIG. IB.
- the reactive inserts 118 are configured to react with a halogen containing species to limit etching or erosion of refractory metal material within the ion source chamber 102. Since both cathode 104 and repeller 108 are constructed from refractory metal, this reduced erosion increases lifetime of both, which improves ion source lifetime.
- the present inventors have discovered that certain combinations of materials used for the reactive inserts 118 and halogen species supplied to the ion source chamber 102 are especially effective in reducing tungsten erosion.
- the so-called halogen cycle entails removal of tungsten atoms in the present of halogen species such as fluorine species from relatively colder surfaces, and their redeposition on relatively hotter surfaces.
- the chemistry and energetics of the arc plasma 116 may be altered in a fashion that reduces tungsten etching.
- an a - alumina (“aluminum oxide” or "AI 2 O 3 ”) insert consisting of a single plate was placed within a tungsten IHC ion source chamber in which a discharge was produced using different fluorinated gases.
- an arc plasma in the ion source was operated for 65 hours while NF 3 was supplied to the ion source chamber. After operation substantial tungsten deposits were observed throughout the ion source chamber including about 1-2 cm thick tungsten deposit on the surface of the cathode.
- an arc plasma in the ion source was operated for 65 hours while NF 3 was supplied to the ion source chamber.
- FIG. 2A illustrates a mass spectrum 200 of ions extracted from an IHC ion source when it is fed with 2.1 seem NF 3 and 0.4 seem H 2
- the mass spectrum which plots ion current as a function of the ratio of ion mass /charge, is characterized by multiple peaks as labeled. These include aluminum species and byproduct species derived from the NF 3 precursor species.
- the spectral region 202 includes a peak representing a current of about 4 mA due to singly charged aluminum Al + whose mass/charge ratio is about 27 amu.
- the mass spectrum 200 also includes a peak 204 and peak 205 indicative of A1F 2 and A1F respectively, which may form as a result of the reaction of fluorine species derived from NF 3 with the A1 2 0 3 insert. Also present in the mass spectrum 200 is a broad peak 206 (which is a convolution of six isotopes) whose peak current is about 1 mA and is attributable to W 2+ . These results indicate that a substantial amount of tungsten elemental species are produced in the ion source discharge under gas flow conditions of 2.1 seem NF 3 and 0.4 seem H 2 , in concert with the observation of large amounts of redeposited tungsten on the cathode after 65 hours operation.
- FIG. 2B illustrates a mass spectrum 210 collected from ions extracted from the IHC ion source when 2.3 seem BF 3 is provided to the ion source chamber.
- the spectral region 212 includes a peak representing a current of about 4.5 mA due to singly charged aluminum Al + whose mass/charge ratio is about 27 amu.
- the mass spectrum 210 shows a very small peak in the region 214 is attributable to W 2+ .
- FIG. 2C when an extended mass spectrum 220 was collected up to 200 amu/charge, the peaks 222 and 224, indicative of W 2+' and W + , respectively, are very small with respect to the Al + peak.
- the plasma is electrically quasi-neutral which means the number of ions is equal with the number of electrons.
- the difference in potential between the plasma plume (arc plasma) and the cathode potential (called “cathodic fall") is relatively high.
- the cathodic fall adjusts to become larger, thereby leading to higher kinetic energy of ions leaving the plasma plume. This fact results in higher secondary electron emission from the cathode under ion bombardment.
- the increased electron emission allows the plasma to maintain a dynamic equilibrium. If plasma density is relatively high, the cathodic fall becomes relatively small. In such a case, to maintain the equilibrium, the smaller ion energy imparted to ions accelerated from the plasma to the cathode is compensated by the higher number of ions that bombard the cathode.
- the change in plasma properties between a BF 3 plasma and NF 3 plasma may be explained at least in part by the difference in ionization potentials of generated species in the BF 3 plasma as opposed to the NF 3 plasma.
- Table I illustrates ionization energies for several species of interest in BF 3 plasmas and NF 3 plasmas.
- the term "ionization energy" as used herein refers to the first ionization energy.
- the BF 3 molecules may dissociate into BF 2 , BF, and B, among other species.
- each of these dissociation product species has an ionization energy in the range of 8-11 eV, which is substantially lower than the ionization energy for dissociation products of an NF 3 plasma including F (17.42 eVO, N (14.71 eV) and N 2 (15.75 eV).
- F 17.42 eVO, N (14.71 eV) and N 2 (15.75 eV).
- gaseous species derived from the alumina insert itself may serve to adjust the plasma properties.
- gaseous species derived from the alumina insert itself may serve to adjust the plasma properties.
- aluminum and aluminum fluoride products are believed to be produced in plasmas where aluminum oxide is exposed to fluorine-containing precursors.
- aluminum metal has a first ionization potential of 5.99 eV
- aluminum species generated from the alumina insert may serve to increase plasma density in the NF 3 based plasma or BF 3 based plasmas when aluminum is etched from the alumina insert.
- ionization thresholds for dissociation products shown above is about 15 eV or higher
- the aluminum species do not exert a sufficient contribution to increase plasma density to the extent that ion energy is reduced to the point where tungsten metal sputtering is suppressed.
- the combination of alumina insert and BF 3 both of which yield species having ionization energies below 11 eV, is sufficient to generate a high enough plasma density and therefore lower ion bombardment energy to suppress sputtering of tungsten within the ion source chamber.
- the reactive inserts 118 may be made from solid silicon. During operation of the ion source 100 the solid silicon may act as a sacrificial material that is preferentially etched by fluorinated gases or fluorine radicals, thus inhibiting the etching and deposition of tungsten or molybdenum surfaces of the ion source chamber 102.
- the reactive inserts 118 are configured as solid silicon inserts and BF 3 gas is provided to the ion source chamber 102. Fluorine and fluorinated gases may readily react with silicon to produce silicon fluorides such as SiF 2 and SiF 4 each of which is a gas phase species at typical operating temperatures of the ion source chamber 102.
- Such SiF 2 and SiF 4 products may therefore be readily pumped out of the ion source chamber 102 during operation.
- the presence of silicon in the reactive inserts 118 inhibits the etching of tungsten material, exposed surfaces, such as tungsten surfaces in the ion source chamber 102 may still react with fluorine containing gas species to some extent, yielding tungsten fluorides.
- the tungsten fluorides may, in turn, react with the reactive (silicon) insert 118 to produce silicon fluorides while reducing the tungsten fluorides to tungsten metal.
- the reactive inserts 118 present a silicon surface that is exposed to the arc plasma 116 during operation of the ion source 100, sputtering of the Si surface by ions from the discharge 116 may prevent a passivating layer of tungsten from forming on the reactive inserts 118.
- the reactive inserts 118 when configured as silicon inserts presents a continuous supply of etchable silicon that reduces the etching of tungsten or other refractory metal from surfaces within the ion source chamber 102.
- a silicon material for reactive inserts 118 in concert with a gas such as BF 3 is effective in reducing of the etching and redeposition of refractory metal on the cathode 104, repeller 108, and elsewhere within the ion source chamber 102, thus increasing the ion source lifetime.
- FIG. 3 presents results of the experiments including a mass spectrum 302 collected during IHC ion source operation with a silicon insert (continuous line) and a mass spectrum 304 collected during IHC ion source operation without a silicon insert (dashed line).
- Each mass spectrum includes a series of peaks representing different mass/charge ratios as described above.
- the mass spectrum 302 includes several peaks 306, 308, 310, 312, 314, 316 that represent silicon ions or silicon fluoride ions as shown.
- the mass spectrum 304 includes a peak 318 that is not present (or greatly reduced) in the mass spectrum 302.
- the peak 318 may be assigned to W 2+ thereby indicating the presence of substantial tungsten species in the arc plasma when silicon inserts are absent.
- the reduction of W 2+ peak at a mass/charge ratio of about 92 amu in the mass spectrum 302 indicates that the halogen cycle is substantially suppressed by the use of the silicon inserts.
- An advantage of embodiments in which silicon is used as a reactive insert include the fact that in addition to reducing etching of metallic surfaces of the ion source, no additional metallic species are introduced into the arc plasma from the silicon inserts.
- the presence of a sacrificial silicon insert increases the supply of gas phase silicon that is ionized in an arc plasma and thereby increases the silicon beam current that can be extracted from the ion source at a given power level.
- reactive inserts that are effective to suppress etching of refractory metal surfaces in the ion source chamber need only occupy a relatively small portion of the ion source chamber.
- the reactive insert or inserts may have a surface area Al that is a fraction of the surface area A2 that includes of the internal walls of ion source chamber, the cathode, and repeller. In some cases A1/A2 equals about 0.01 to 0.2. Accordingly, a reactive insert or inserts whose surface area constitutes such a modest fraction of the surface area presented by refractory metal surfaces, does not require substantial redesign of other components of an ion source.
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Abstract
Description
Claims
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
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JP2016512065A JP2016522964A (en) | 2013-05-03 | 2014-05-02 | Extended life ion source |
CN201480037223.3A CN105340049B (en) | 2013-05-03 | 2014-05-02 | Ion source and operation method thereof |
KR1020157034280A KR101699841B1 (en) | 2013-05-03 | 2014-05-02 | Ion source and method to operate the same |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
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US13/886,683 | 2013-05-03 | ||
US13/886,683 US9187832B2 (en) | 2013-05-03 | 2013-05-03 | Extended lifetime ion source |
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WO2014179677A1 true WO2014179677A1 (en) | 2014-11-06 |
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PCT/US2014/036558 WO2014179677A1 (en) | 2013-05-03 | 2014-05-02 | Extended lifetime ion source |
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US (1) | US9187832B2 (en) |
JP (1) | JP2016522964A (en) |
KR (1) | KR101699841B1 (en) |
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US9818570B2 (en) * | 2015-10-23 | 2017-11-14 | Varian Semiconductor Equipment Associates, Inc. | Ion source for multiple charged species |
GB2567853B (en) | 2017-10-26 | 2020-07-29 | Isotopx Ltd | Gas-source mass spectrometer comprising an electron source |
US10347457B1 (en) * | 2017-12-19 | 2019-07-09 | Varian Semiconductor Equipment Associates, Inc. | Dynamic temperature control of an ion source |
US10892137B2 (en) | 2018-09-12 | 2021-01-12 | Entegris, Inc. | Ion implantation processes and apparatus using gallium |
CN109600895B (en) * | 2018-11-15 | 2020-11-10 | 合肥聚能电物理高技术开发有限公司 | High density hot cathode plasma source |
JP7325597B2 (en) * | 2019-03-18 | 2023-08-14 | 住友重機械イオンテクノロジー株式会社 | Ion generator and ion implanter |
JP7256711B2 (en) * | 2019-07-16 | 2023-04-12 | 住友重機械イオンテクノロジー株式会社 | Ion generator and ion implanter |
US12033843B2 (en) * | 2020-03-26 | 2024-07-09 | Agilent Technologies, Inc. | Mass spectrometry ION source |
US20210261790A1 (en) * | 2021-05-03 | 2021-08-26 | Silcotek Corp. | Coated systems for hydrogen |
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TW201503206A (en) | 2015-01-16 |
CN105340049A (en) | 2016-02-17 |
CN105340049B (en) | 2017-04-26 |
JP2016522964A (en) | 2016-08-04 |
TWI571901B (en) | 2017-02-21 |
KR101699841B1 (en) | 2017-01-25 |
US20140326594A1 (en) | 2014-11-06 |
US9187832B2 (en) | 2015-11-17 |
KR20160003248A (en) | 2016-01-08 |
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